plucky (3) critcl_emap.3tcl.gz
NAME
critcl::emap - CriTcl - Wrap Support - Enum en- and decoding
SYNOPSIS
package require Tcl 8.6
package require critcl ?3.2?
package require critcl::emap ?1.3?
::critcl::emap::def name definition ?-nocase? ?-mode mode?
________________________________________________________________________________________________________________
DESCRIPTION
Be welcome to the C Runtime In Tcl (short: CriTcl), a system for embedding and using C code from within
Tcl [http://core.tcl-lang.org/tcl] scripts.
This document is the reference manpage for the critcl::emap package. This package provides convenience
commands for advanced functionality built on top of both critcl core and package critcl::iassoc.
C level libraries often use enumerations or integer values to encode information, like the state of a
system. Tcl bindings to such libraries now have the task of converting a Tcl representation, i.e. a
string into such state, and back. Note here that the C-level information has to be something which
already exists. The package does not create these values. This is in contrast to the package critcl::enum
which creates an enumeration based on the specified symbolic names.
This package was written to make the declaration and management of such enumerations and their associated
conversions functions easy, hiding all attendant complexity from the user.
Its intended audience are mainly developers wishing to write Tcl packages with embedded C code.
This package resides in the Core Package Layer of CriTcl.
+----------------+
|Applications |
| critcl |
| critcl::app |
+----------------+
*================*
|Core Packages |
| critcl |
| critcl::util |
*================*
+----------------+
|Support Packages|
| stubs::* |
| md5, platform |
| ... |
+----------------+
API
::critcl::emap::def name definition ?-nocase? ?-mode mode?
This command defines C functions for the conversion of the named state code into a Tcl string, and
vice versa. The underlying mapping tables are automatically initialized on first access (if not
fully constant), and finalized on interpreter destruction.
The definition dictionary provides the mapping from the Tcl-level symbolic names of the state to
their C expressions (often the name of the macro specifying the actual value). Note here that the
C-level information has to be something which already exists. The package does not create these
values. This is in contrast to the package critcl::enum which creates an enumeration based on the
specified symbolic names.
Further note that multiple strings can be mapped to the same C expression. When converting to Tcl
the first string for the mapping is returned. An important thing to know: If all C expressions are
recognizable as integer numbers and their covered range is not too large (at most 50) the package
will generate code using direct and fast mapping tables instead of using a linear search.
If the option -nocase is specified then the encoder will match strings case-insensitively, and the
decoder will always return a lower-case string, regardless of the string's case in the definition.
If the option -mode is specified its contents will interpreted as a list of access modes to
support. The two allowed modes are c and tcl. Both modes can be used together. The default mode
is tcl.
The package generates multiple things (declarations and definitions) with names derived from name,
which has to be a proper C identifier. Some of the things are generated conditional on the chosen
modes.
name_encode
The tcl-mode function for encoding a Tcl string into the equivalent state code. Its
signature is
int name_encode (Tcl_Interp* interp, Tcl_Obj* state, int* result);
The return value of the function is a Tcl error code, i.e. TCL_OK, TCL_ERROR, etc.
name_encode_cstr
The c-mode function for encoding a C string into the equivalent state code. Its signature
is
int name_encode_cstr (const char* state);
The return value of the function is the encoded state, or -1 if the argument is not a vlaid state.
name_decode
The tcl-mode function for decoding a state code into the equivalent Tcl string. Its
signature is
Tcl_Obj* name_decode (Tcl_Interp* interp, int state);
name_decode_cstr
The c-mode function for decoding a state code into the equivalent C string. Its signature
is
const char* name_decode_cstr (int state);
The return value of the function is the C string for the state, or NULL if the state argument does
not contain a valid state value.
name.h A header file containing the declarations for the conversion functions, for use by other
parts of the system, if necessary.
The generated file is stored in a place where it will not interfere with the overall system
outside of the package, yet also be available for easy inclusion by package files
(csources).
name For mode tcl the command registers a new argument-type for critcl::cproc with critcl,
encapsulating the encoder function.
name For mode tcl the command registers a new result-type for critcl::cproc with critcl,
encapsulating the decoder function.
EXAMPLE
The example shown below is the specification for the possible modes of entry (normal, no feedback, stars)
used by the Tcl binding to the linenoise library.
package require Tcl 8.6
package require critcl 3.2
critcl::buildrequirement {
package require critcl::emap
}
critcl::emap::def hiddenmode {
no 0 n 0 off 0 false 0 0 0
all 1 yes 1 y 1 on 1 true 1 1 1
stars 2
} -nocase
# Declarations: hiddenmode.h
# Encoder: int hiddenmode_encode (Tcl_Interp* interp, Tcl_Obj* state, int* result);
# Decoder: Tcl_Obj* hiddenmode_decode (Tcl_Interp* interp, int state);
# ResultType: hiddenmode
# ArgumentType: hiddenmode
AUTHORS
Andreas Kupries
BUGS, IDEAS, FEEDBACK
This document, and the package it describes, will undoubtedly contain bugs and other problems. Please
report such at https://github.com/andreas-kupries/critcl. Please also report any ideas for enhancements
you may have for either package and/or documentation.
KEYWORDS
C code, Embedded C Code, Tcl Interp Association, bitmask, bitset, code generator, compile & run,
compiler, dynamic code generation, dynamic compilation, flags, generate package, linker, on demand
compilation, on-the-fly compilation, singleton
CATEGORY
Glueing/Embedded C code
COPYRIGHT
Copyright (c) 2011-2024 Andreas Kupries